Reliability, validity, and responsiveness of the Japanese version of International Restless Legs Syndrome Study Group rating scale for restless legs syndrome in a clinical trial setting

Restless legs syndrome augmentation among Japanese patients receiving pramipexole therapy: Rate and risk factors in a retrospective study

To investigate the rate of and risk factors for restless legs syndrome (RLS) augmentation in Japanese patients receiving pramipexole (PPX) treatment. Records of 231 consecutive patients with idiopathic RLS who received PPX therapy for more than one month in a single sleep disorder center were analyzed retrospectively. Augmentation was diagnosed based on the Max Planck Institute criteria; associated factors were identified by logistic regression analysis. Mean age at PPX initiation was 60.6 ± 14.9 years and mean treatment duration was 48.5 ± 26.4 months. Augmentation was diagnosed in 21 patients (9.1%). Daily PPX dose and treatment duration were significantly associated with augmentation. By analyzing the receiver operating characteristic curve, a PPX dose of 0.375 mg/day was found to be the optimal cut-off value for predicting augmentation. After stratifying patients according to PPX treatment duration, at median treatment duration of 46 months, optimal cut-off values for daily doses were 0.375 and 0.500 mg/day for <46 months and ≥46 months of treatment, respectively. The RLS augmentation with PPX treatment in Japanese patients was occurred at rate of 9.1%, being quite compatible with previously reported rates in Caucasian patients. The symptom could appear within a relatively short period after starting the treatment in possibly vulnerable cases even with a smaller drug dose. Our results support the importance of keeping doses of PPX low throughout the RLS treatment course to prevent augmentation.

Review of Severity Rating Scales for Restless Legs Syndrome: Critique and Recommendations

Over the last decade, research in restless legs syndrome (RLS; also known as Willis-Ekbom disease) has increased dramatically. The International Parkinson and Movement Disorder Society commissioned a task force to formally evaluate the available evidence on severity rating scales in RLS. A literature search retrieved instruments specific to RLS. Each scale was evaluated by three criteria: (1) use in RLS; (2) use by research or clinical groups other than the group that developed the scale; and (3) formal validation and adequate clinimetric properties. Scales were then qualified as "recommended" when all three criteria were met, "suggested" when used for RLS but only one of the other criteria was met, and "listed" when only used in RLS. Details regarding the development, use, and psychometric properties of each instrument and the recommendations of the committee are summarized. The scale of the International Restless Legs Syndrome Study Group for rating the severity of RLS (International Restless Legs Scale or IRLS) and the Augmentation Severity Rating Scale fulfilled criteria for "recommended" instruments to assess severity. Future endeavors should include a validation of the Pediatric RLS Severity Scale, the only available instrument for evaluation of the severity of pediatric RLS, and a validation of a patient version of the IRLS that will not require the interface of a live interviewer.